fix: Flaky AppLayout error boundaries tests

[georgylobko]

Description

Fixed tests flakiness for AppLayout error boundaries by adding waitForAssertion.

Related links, issue #, if available: n/a

How has this been tested?

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.45%. Comparing base (7364de0) to head (e4a84a0).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4402   +/-   ##
=======================================
  Coverage   97.45%   97.45%           
=======================================
  Files         909      909           
  Lines       26638    26638           
  Branches     9615     9615           
=======================================
  Hits        25959    25959           
  Misses        673      673           
  Partials        6        6           

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